Revert "Merge pull request #253 from ojacobson/preserve-original-build-dir"
Revert "Merge pull request #253 from ojacobson/preserve-original-build-dir"

This reverts commit 1e5ff1f8c926e3405679477519aa33da1874dc11, reversing
changes made to 83538ca6ecbdcf5802634aacaa1c2c3d98fd297e.

Scalingo/python-buildpack,heroku/heroku-buildpack-python,doda/heroku-buildpack-python,zakdoek/heroku-buildpack-django,andela-brotich/wger-buildpack-python,samuelhavron/heroku-buildpack-python,cloudfoundry/python-buildpack,jimlindeman/python-buildpack-collectd,Nazanin84/python-buildpack,jamarparris/heroku-buildpack-python-swig,slorg1/heroku-buildpack-python,loanzen/heroku-buildpack-python,smalleats/heroku-buildpack-python,benjaminfox/heroku-buildpack-python-geoip,heroku/heroku-buildpack-python,andrespires/python-buildpack,ojacobson/heroku-buildpack-python,grivescorbett/heroku-buildpack-python,cloudfoundry/python-buildpack,maciejgryka/heroku-buildpack-spcedge,jimlindeman/python-buildpack-collectd,AltSchool/heroku-buildpack-python,samuelhavron/heroku-buildpack-python,pkumar-appd/python-buildpack,samuelhavron/heroku-buildpack-python,andrespires/python-buildpack,cclauss/heroku-buildpack-python,jimlindeman/python-buildpack-collectd,samuelhavron/heroku-buildpack-python,cloudfoundry/python-buildpack,driftyco/heroku-buildpack-sphinx,samuelhavron/heroku-buildpack-python,plangrid/heroku-buildpack-python,pkumar-appd/python-buildpack,edenspiekermann-amsterdam/heroku-buildpack-python,zakdoek/heroku-buildpack-django,Nazanin84/python-buildpack,andrespires/python-buildpack,Nazanin84/python-buildpack,gitricko/apt-python-buildpack,edmorley/heroku-buildpack-python,samuelhavron/heroku-buildpack-python,joshfriend/heroku-buildpack-python,samuelhavron/heroku-buildpack-python,doda/heroku-buildpack-python,samuelhavron/heroku-buildpack-python,HanSooloo/heroku-buildpack-python,ad-m/heroku-buildpack-python,DylanLukes/heroku-buildpack-python,jvenezia/heroku-buildpack-python,benmurden/heroku-buildpack-python-ember,miraculixx/heroku-buildpack-python,benjaminfox/heroku-buildpack-python-geoip,benmurden/heroku-buildpack-python-ember,swanson/heroku-buildpack-python-ortools,skilljar/heroku-buildpack-python,gaumire/heroku-buildpack-python,AltSchool/heroku-buildpack-python,pmclanahan/heroku-buildpack-python-peep,ad-m/heroku-buildpack-python,Scalingo/python-buildpack,gitricko/apt-python-buildpack,pkumar-appd/python-buildpack,wbrefvem/heroku-buildpack-python,gitricko/apt-python-buildpack,wbrefvem/heroku-buildpack-python